Although a number of systems for changing aircraft propeller pitch have been proposed, many previous systems are designed to provide a change in propeller pitch which occurs at a constant predetermined rate and/or which cannot change in rate depending on conditions or under the control of the pilot. It has been found that there are certain circumstances in which it would be desirable to change propeller pitch at different rates. For example, during flight conditions, it is typically preferred to provide a relatively slow rate of pitch change such as providing for a change between about 1/10 and about 2/3 degree per second, commonly about 1/3 degree change in pitch per second. In taxiing or other on-ground conditions, however, it would desirable to provide for more rapid change in propeller pitch, e.g. to provide for greater maneuverability on the ground. There is a particular need for the greater maneuverability which could result from rapid propeller pitch change in connection with sea planes which are attempting to maneuver on the water, e.g. approaching a dock or other structure.
On the other hand, a rapid change in pitch during flight conditions might best be avoided, e.g. to avoid loss of control or excess stress on propeller or other parts. Many previous devices fail to include a system to avoid rapid pitch changes or to prevent switching to a rapid pitch change rate during certain conditions, e.g. typical flight conditions.
Additionally, a number of variable pitch systems are relatively expensive, thus placing the benefits of variable pitch, and particularly multiple-speed of pitch change, in a cost range which is impractical or infeasible for small (e.g. single engines), experimental, light or hobbyist aircraft.
Accordingly, it would be advantageous to provide an aircraft propeller system which permitted changing the propeller pitch at two or more different rates, preferably depending on the condition of the aircraft or under control of the pilot. It would further be advantageous to provide a system which would prevent high or excessive pitch change rates during flight or other conditions. Additionally, it would be advantageous to provide such a system which would be sufficiently inexpensive to make it feasible for use in small, experimental, light or hobbyist planes yet which is reliable, safe, durable and easy to use and/or maintain.